{"id":783,"date":"2019-12-01T07:33:05","date_gmt":"2019-12-01T07:33:05","guid":{"rendered":"https:\/\/golangbyexamples.com\/?p=783"},"modified":"2019-12-01T07:35:58","modified_gmt":"2019-12-01T07:35:58","slug":"function-method-overloading-golang","status":"publish","type":"post","link":"https:\/\/golangbyexamples.com\/function-method-overloading-golang\/","title":{"rendered":"Function\/Method Overloading in Golang (Alternatives\/Workaround)"},"content":{"rendered":"\n<p class=\"has-medium-font-size\">Function\/Method Overloading means that that the same function\/method name can be used with a different number and types of parameters<\/p>\n\n\n\n<p class=\"has-medium-font-size\">See this post for difference between function and method in Go &#8211; <a href=\"https:\/\/golangbyexamples.com\/difference-between-method-function-go\">https:\/\/golangbyexamples.com\/difference-between-method-function-go<\/a><\/p>\n\n\n\n<p>Eg. <\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">func X()\nfunc X(name string)\nfunc X(name, address string)\nfunc X(name string, age int)<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Go doesn&#8217;t support method\/function overloading. See this faq for the reason <a href=\"https:\/\/golang.org\/doc\/faq#overloading\">https:\/\/golang.org\/doc\/faq#overloading<\/a><\/p>\n\n\n\n<p class=\"has-medium-font-size\">According to the above faq things are simpler without it.<\/p>\n\n\n\n<p class=\"has-medium-font-size\">We can workaround Method\/Function overloading in GO using<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\"><li><strong>Variadic Function<\/strong> &#8211; A Variadic Function is a function that accepts a variable number of arguments<\/li><li><strong>Empty Interface<\/strong> &#8211; It is an interface without any methods.<\/li><\/ul>\n\n\n\n<p class=\"has-medium-font-size\">There are two cases for Method\/Function Overloading<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p style=\"font-size:24px\">1.<strong>Different number of parameters but of the same type:<\/strong><\/p>\n\n\n\n<p class=\"has-medium-font-size\">Above case can easily be handled using variadic functions. Notice in below code the parameters are of one type i.e. <strong>int.<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport \"fmt\"\n\nfunc main() {\n    fmt.Println(add(1, 2))\n    fmt.Println(add(1, 2, 3))\n    fmt.Println(add(1, 2, 3, 4))\n}\n\nfunc add(numbers ...int) int {\n    sum := 0\n    for _, num := range numbers {\n        sum += num\n    }\n    return sum<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output:<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">3\n6\n10<\/code><\/pre>\n\n\n\n<p><\/p>\n\n\n\n<p style=\"font-size:24px\">2.<strong>Different number of parameters and of different types<\/strong><\/p>\n\n\n\n<p class=\"has-medium-font-size\">This case can be handled using both variadic function and empty interface<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport \"fmt\"\n\nfunc main() {\n    handle(1, \"abc\")\n    handle(\"abc\", \"xyz\", 3)\n    handle(1, 2, 3, 4)\n}\n\nfunc handle(params ...interface{}) {\n    fmt.Println(\"Handle func called with parameters:\")\n    for _, param := range params {\n        fmt.Printf(\"%v\\n\", param)\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output:<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Handle func called with parameters:\n1\nabc\nHandle func called with parameters:\nabc\nxyz\n3\nHandle func called with parameters:\n1\n2\n3\n4<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">We can also use a switch case to get the exact parameters and use them accordingly. See the below example.<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport \"fmt\"\n\ntype person struct {\n    name   string\n    gender string\n    age    int\n}\n\nfunc main() {\n    err := addPerson(\"Tina\", \"Female\", 20)\n    if err != nil {\n        fmt.Println(\"PersonAdd Error: \" + err.Error())\n    }\n    \n    err = addPerson(\"John\", \"Male\")\n    if err != nil {\n        fmt.Println(\"PersonAdd Error: \" + err.Error())\n    }\n     \n    err = addPerson(\"Wick\", 2, 3)\n    if err != nil {\n        fmt.Println(\"PersonAdd Error: \" + err.Error())\n    }\n}\n\nfunc addPerson(args ...interface{}) error {\n    if len(args) > 3 {\n        return fmt.Errorf(\"Wront number of arguments passed\")\n    }\n    p := &person{}\n    \/\/0 is name\n    \/\/1 is gender\n    \/\/2 is age\n    for i, arg := range args {\n        switch i {\n        case 0: \/\/ name\n            name, ok := arg.(string)\n            if !ok {\n                return fmt.Errorf(\"Name is not passed as string\")\n            }\n            p.name = name\n        case 1:\n            gender, ok := arg.(string)\n            if !ok {\n                return fmt.Errorf(\"Gender is not passed as string\")\n            }\n            p.gender = gender\n        case 2:\n            age, ok := arg.(int)\n            if !ok {\n                return fmt.Errorf(\"Age is not passed as int\")\n            }\n            p.age = age\n        default:\n            return fmt.Errorf(\"Wrong parametes passed\")\n        }\n    }\n    fmt.Printf(\"Person struct is %+v\\n\", p)\n    return nil\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Note:<\/strong> Wherever the arg is not passed it is substituted as default. <\/p>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output:<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Person struct is &{name:Tina gender:Female age:20}\nPerson struct is &{name:John gender:Male age:0}\nPersonAdd Error: Gender is not passed as string<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Function\/Method Overloading means that that the same function\/method name can be used with a different number and types of parameters See this post for difference between function and method in Go &#8211;&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","footnotes":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false},"categories":[1],"tags":[97,3,4,93,98],"class_list":["post-783","post","type-post","status-publish","format-standard","hentry","category-tech","tag-function","tag-go","tag-golang","tag-method","tag-overloading"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.7 - 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